I saw already alot of posts about this but didnt help my
So I though I ask it myself

I have a fine working PC
2x4 vengeance and 1x4gskill

Windows memory diagnostic showed no problems

Till I downloaded memtest86
And found out I had a error running on test 6
Also I want to fix it.

As normally I broke it first

Cause I removed 2 one by one, but on the last one the problem was solved so I put one back and there it was again tried different slots but all with the same results
So I looked closer at the first one pushed it a little down.
Restarted the PC and it started but had a black screen.
So removed all ram cleaned tried it again NOTTING
So I cleared the cmos by removing the power

I pressed the memok button to start and Its running but still with errors